1. Field of the Invention
This invention relates generally to communication transmitters, receivers, and systems. More particularly, the invention relates to a class of bandwidth efficient modulation schemes and their use in the design and implementation of trellis based modems.
2. Description of the Related Art
Modulation techniques that can pass more information through a fixed bandwidth are generally desirable. Specific needs exist for improved bandwidth-efficient modulation schemes for use in applications like DSL modems, cable modems, broadband wireless access (e.g., WiMAX, 802.16, 802.16a), wireless local area networks (e.g., WiFi, 802.11), personal area networks (e.g., Bluetooth), terrestrial HDTV channels, digital cable TV channels, satellite communications, cellular telephones, wide-area cellular telephony based endpoints (e.g., GSM EDGE, 2.5G, 3G and 4G terminals and base stations), and the like. In all such systems, a “modem” is, a MODulator/DEModulator device that implements at least a physical layer protocol in the transmit and/or receive directions.
U.S. patent application Ser. 11/253,730: “Single sideband and quadrature multiplexed continuous phase modulation” and Ser. No. 11/374,217: “Uplink Modulation and Receiver Structures for Asymmetric OFDMA Systems” are incorporated herein by reference. These US patent applications, written by the same inventors as the instant application, present a broad class of signaling schemes called SSB-FM as defined therein. A subclass of SSB-FM signaling schemes is called quadrature-multiplexed (QM) continuous phase modulation (CPM), i.e., QM-CPM. Multi-amplitude QM-CPM schemes and generalizations thereof were also presented in U.S. patent application Ser. 11/253,730.
Additional species of the genus of inventions presented in the two aforementioned prior US Patent applications would be desirable. In particular, multi-state binary QM-CPM signaling schemes would be advantageous. Similarly, additional efficiencies could be achieved by the advent of higher order M2-ary QM-CPM derived from M-ary CPM (M>2). Given such M2-ary QM-CPM schemes, it would be advantageous to construct N2-ary multi-amplitude QM-CPM by applying multi-amplitude signaling to the M-ary CPM, i.e., (N>M>2, N=LM, L>1). Hybrid multi-amplitude QM-CPM signaling schemes made up of more than one underlying CPM scheme would also be advantageous. These additional species of the previously disclosed SSB-FM and QM-CPM genus-inventions and specific optimized parameter sets that produce especially high performance would be useful.
Also needed are specific generalizations of the QM-CPM species as described in the paragraph above that use any phase modulation (PM) which includes and subsumes frequency modulation (FM), but more generally than CPM, i.e., with or without a continuous phase.